Stabilizing yarn threadline during twisting



Nov. 4, 1969 B. o. GIBSON ET AL 3,475,896

STABILIZING YARN THREADLINE DURING TWISTING Filed April 29, 1968 United States Patent US. Cl. 57-106 Claims ABSTRACT OF THE DISCLOSURE Method and apparatus for drawtwisting non-circular filaments and yarn wherein the yarn passes over a rotary guide or roll having a plurality of circumferential grooves. The guide or roll is positioned between the ring traveler of a conventional spinning frame and the creel in which the yarn package is supported. Preferably, a thread guide having circumferential grooves is positioned directly above the feed roll to avoid twist from the package in the creel reaching the feed rolls, and a grooved separator roll is positioned above the bobbin to avoid twisting the yarns off the draw roll or godet, due to the twist caused by the traveler.

Background of the invention This invention relates to the processing of yarns and filaments, and more particularly to the drawing and twisting of yarns and filaments.

Filaments and yarns that have a non-circular cross section tend to have an unstable threadline when drawtwisting is attempted on a conventional spinning machine. In winding the warn on the bobbin, the ring traveler rotates about the bobbin and in doing so, imparts twist to the yarn. The twist is carried by the yarn back toward the draw roll, or feed roll, until it reaches a surface that resists further transmission of twist.

In spinning cotton, the back up of twist in the spinning machine does not constitute a serious problem, because it can be arrested effectively by a yarn guide placed above the bobbin. Synthetic yarns and filaments having non-circular cross sections are now being manufactured, and some of these yarns experience severe twisting which has been observed to reach the spun yarn bobbin in the creel. Furthermore, the yarn becomes so lively that it wanders sideways out under the cot roll and off the draw roll. Trilobal monofilaments and flat yarn are examples of such non-circular filaments and yarns. Hereafter the term noncircular yarns is used to include both monofilaments and yarns that are non-circular in cross section. These noncircular yarns may be extruded or spun in a variety of methods well known in the art to obtain a denier per filament of up to 55 or more, but generally ranges from about 2 to 25 and preferably from about 3 to 20.

Filament-forming materials employed in the implementation of the present invention may comprise organic derivatives of cellulose such as the esters or ethers thereof, for example cellulose organic acid esters such as cellulose acetate, cellulose propionate, cellulose butyrate, cellulose benzoate, cellulose acetate formate, cellulose acetate propionate, cellulose acetate butyrate, and the like, ethers such as ethyl cellulose, etc. The esters may be ripened and acetone-soluble, such as conventional cellulose acetate, or may be substantially fully esterified, that is, contain fewer than 0.29 free hydroxyl groups per anhydroglucose unit, e.g. cellulose triacetate.

The filament-forming materials may also comprise a variety of other thermoplastic or solvent-soluble polymeric materials such as super-polyamides, e.g. nylon, superpolyesters such as polyethylene terephthalate, polyglycolic acid and copolymers thereof, acrylonitrile polymers and copolymers, polymers and copolymers of olefins and vinyl esters such as ethylene, propylene, vinyl chloride, vinyl acetate, vinylidene chloride and vinylidene cyanide, and the like.

The controlled twisting of these yarns is desirable when the yarns are used in knitting apparatus, for example, because the twist helps to retain the yarn in the eye of the knitting needle.

In view of the instability of the threadline while drawtwisting non-circular yarn, it is an object of this invention to provide apparatus for stabilizing the threadline.

It is another object of this invention to provide apparatus for preventing twist by the package in the creel from reaching the feed rolls.

Another object of this invention is to provide apparatus for preventing twist backed up by the traveler from displacing the yarn off the draw roll.

Summary of the invention These objects are accomplished in accordance with a preferred embodiment of the invention by positioning a rotary, grooved yarn guide on the traverse bar above the cot roll. The yarn makes a plurality of passes over the rotary yarn guide and over the cot roll before making a plurality of wraps over the feed roll. The yarn then passes to the draw roll or godet roll. Directly above the draw roll is a grooved, rotary separator roll. The yarn makes a plurality of passes over the draw roll and the separator roll, and then is conducted through a yarn guide to the traveler on the traversing ring rail to the rotating bobbin. The grooved rotary yarn guide arrests twist imparted by the removal of yarn from the package in the creel and provides a continuous guide for the yarn as it passes over the cot roll and the feed roll. The separator roll effectively arrests twist back-up and stabilizes the threadline.

Detailed description of the drawings This preferred embodiment is illustrated in the accompanying drawings in which:

FIG. 1 is a schematic view of apparatus for twisting yarn in accordance with this invention;

FIG. 2 is a front elevational view of the yarn guide; and

FIG. 3 is an elevational view of the separator roll.

Description of the preferred embodiment Referring to FIG. 1, a yarn package 2 is shown schematically in FIG. 1 as mounted in the creel of a twister. Adjacent the yarn package 2 is a conventional pretension guide 4. Below the pretension guide 4, a conventional traverse bar 6 is mounted on the twister. An arm 8 extends outwardly from the traverse bar 6 and a rotary guide 10 is journaled on ball bearings on a shaft 12 which extends outwardly from the side of the arm 8, as shown in FIG. 2. The guide 10 is in the form of a cylinder and has a plurality of circumferential grooves 14 spaced uniformly along the length of the guide roll 10.

Directly below the guide roll 10 is the cot roll 16 which is mounted for rotation on an arm 18 that extends outwardly from the frame of the twister. The cot roll 16 cooperates with a feed roll 20. The feed roll 20 of a typical twister extends substantially the full length of the machine and rotation is imparted to the feed roll 20 by a motor or other suitable means. The cot roll 16 rests on the feed roll 20 and is driven by the feed roll. Below the feed roll 20, a draw roll 22 is mounted for rotation in the frame of the twister. The draw roll 22 has a smooth, cylindrical surface. Directly above the draw roll, a grooved separator roll 24 is mounted for rotation. The central axis of the roll 24 is approximately parallel to the central axis of the draw roll 22. The separator roll 24 has a cylindrical surface and a plurality of circumferential grooves 26 are provided in the surface of the roll 24.

Below the draw roll 22 is a conventional yarn guide 28 and a conventional ring roll 30 which traverses vertically with respect to a bobbin 32 that is mounted on a rotary spindle extending vertically through an opening in the rail 30. A traveler 34 guides the yarn onto the bobbin 32 as the bobbin rotates.

The non-circular yarn may be a trilobal monofilament which has a shape in cross section which resembles a three pointed star. Other shapes include bilaminar filaments having oval, triangular or rectangular cross sections, A, H, Y, T and the like cross sections, dog bone, modified dog bone, crennladed and the like cross sections as well as side by side conjugate yarns, etc.

The yarn is indicated at 36 in FIG. 1. The yarn passes from the yarn package 2 over the pretension guide 4 and is wound on the guide roll and the cot roll 16. The wrapping of yarn around the feed roll 10 and the cot roll 16 is shown in detail in FIG. 2. The yarn 36 passes down over the front of the guide roller 10, as shown in FIG. 2, and behind the cot roller 16 which rotates counterclockwise as viewed in FIG. 1. The yarn then passes through the nip between the cot roll and feed roll 20 and then passes over the guide roll 10, being positioned in the middle groove 14. The yarn 10 passes back under the cot roll 16 for another wrap and then passes over the guide roll 10, being received in the right hand groove 14, as viewed in FIG. 2. From the feed roll 10, the yarn passes through the nip between the cot roll 16 and the feed roll 20, and is wrapped approximately three times on the feed roll before passing down to the draw roll 22.

The arrangement of wraps on the draw roll 22 and the separator roll 24 is shown schematically in FIGS. 1 and 3. The yarn 36 from the feed roll 20 passes under the draw roll 32 and upwardly behind the separator roll 24, where it is received in the right hand groove 26, as viewed in FIG. 3. The yarn 36 then passes from the separator roll 24 down and under the draw roll and repeats this arrangement until five passes over the separator 24 have been made. After leaving the left hand groove 26, as viewed in FIG. 3, the yarn passes down through the yarn guide 28 to the traveler 34 from which the yarn is wound on the bobbin 32.

The grooves 14 and 26 in the guide roll 10 and separator roll 24, respectively, are considerably wider and deeper than the maximum transverse dimension of the yarn 36. The grooves should be sufiiciently wide to avoid rubbing the yarn against the sides of the groove as the yarn passes over the roll. Preferably, the width and depth of the grooves are both about ten times the maximum transverse dimension of the yarn. The grooves restrict the lateral displacement of the yarn, which otherwise would be twisted off the adjacent smooth roll, and by passing the yarn several times over the guide roller 10 and separator roll 24, considerable stability is imparted to the yarn. The guide roll 10 is particularly effective in arresting instability in the threadline due to twisting of yarn from the yarn package 2 in the creel.

The stability of the yarn during twisting by the apparatus of this invention results in yarn having a substantially uniform degree of twist throughout its length. Furthermore, the twisting operation proceeds without interruption due to the yarn becoming disengaged from the draw roll or feed roll, as in conventional apparatus.

We claim:

1. In twisting apparatus of the type having a feed roll and a cot roll cooperating with said feed roll, the improvement comprising cylindrical guide means adjacent said cot roll, means for rotating said guide means about the central axis thereof, said guide means including a traverse bar adjacent said cot roll and feed roll, and means for oscillating said traverse bar longitudinally of said feed roll and cot roll, said guide means being mounted on said traverse bar, said guide means also including a plurality of radial circumferential grooves in the external surface thereof, said grooves being spaced longitudinally of said cylindrical guide means, whereby yarn is guided over said cot roll and feed roll and said guide means resist lateral displacement of the yarn due to twisting.

2. In apparatus for drawing and twisting yarn of the type having a ring traveler for winding yarn on a bobbin, the improvement comprising a draw roll positioned in a backward direction along the threadline from said traveler, a separator roll mounted adjacent said draw roll, said separator roll being journaled for rotation about an axis substantially parallel to the axis of rotation of said draw roll, said separator roll having a plurality of radial grooves extending around the circumference of the roll, and said grooves being spaced longitudinally along said roll, whereby yarn passing over the draw roll and the separator roll is retained in position by the grooves on the separator roll and resists displacement of the yarn off the draw roll due to twisting of the yarn, said apparatus including a feed roll and cot roll positioned back along the threadline from the draw roll and a guide roll mounted adjacent said cot roll and feed roll, said guide roll having a plurality of radial grooves in the external surface thereof, said grooves being substantially parallel and being spaced apart longitudinally of the roll, whereby yarn passing over the guide roll is prevented from being displaced oh the cot roll and the feed roll due to twisting of the yarn.

3. The apparatus of claim 2 wherein the guide roll is mounted with means for the traverse thereof.

4. The apparatus according to claim 2 wherein the grooves in said guide roll and separator roll are about ten times wider than the maximum transverse dimension of the yarn.

5. In a method for stabilizing a threadline during draw twisting of a yarn having a non-circular cross section wherein the yarn is drawn and twisted with the twist running backwards along the threadline through the drawing zone, the improvement comprising conveying a non-circular yarn from a feed source over a guide roll having at least one circumferential groove in the external surface thereof, subsequently passing said yarn over a smooth feed roll to a drawing zone, drawing said yarn, passing said yarn between a smooth draw roll and a grooved separator roll and subsequently to a twisting zone, twisting said yarn and backing the twist up the yarn along its length through the draw zone to at least the smooth feed roll, thereby creating a sideward torque of said yarn in said zones which is stabilized by said grooved rolls and taking up a twisted yarn on a package.

References Cited UNITED STATES PATENTS 2,172,497 9/1939 Cadden 5755.5 XR 2,988,866 6/1961 Kleekamm et a1. 57-55.5 3,025,660 3/ 1962 Gonsalves 57-55.5 XR 3,073,001 1/1963 Kroll 28-713 3,073,003 1/1963 Fritzemeier 28-713 XR 3,081,593 3/1963 Meerdink 57-55.5 XR 3,137,033 6/1964 Maaskant 28-713 XR 3,169,360 2/1965 Corrall et a1 57-34 3,339,355- 9/ 1967 ONeill 57-36 XR DONALD E. WATKINS, Primary Examiner US. Cl. X.R. 

